title: Keratinocyte growth factor and glucocorticoid induction of human peroxiredoxin 6 gene expression occur by independent mechanisms that are synergistic.
abstract: OBJECTIVE
  Peroxiredoxin 6 (Prdx6), a 1-cys Prdx has both peroxidase and phospholipase A2 activities, protecting against oxidative stress and regulating pulmonary surfactant phospholipid metabolism. This study determined the mechanism by which keratinocyte growth factor (KGF) and the glucocorticoid analogue, dexamethasone (Dex), induce increased Prdx6 expression.
  
  
  RESULTS
  Transcriptional activation by KGF in both A549 lung adenocarcinoma cells and rat lung alveolar epithelial type II (ATII) cells utilizes an antioxidant response element (ARE), located between 357 and 349 nucleotides before the PRDX6 translational start, that is also necessary for upregulation of the human PRDX6 promoter in response to oxidative stress. Activation is mediated by binding of the transcription factor, Nrf2, to the ARE as shown by experiments using siRNA against Nrf2 and by transfecting ATII cells isolated from lungs of Nrf2 null mice. KGF triggers the migration of Nrf2 from cytoplasm to nucleus where it binds to the PRDX6 promoter as shown by chromatin immunoprecipitation assays. Activation of transcription by Dex occurs through a glucocorticoid response element located about 750 nucleotides upstream of the PRDX6 translational start.
  
  
  METHODS
  This study demonstrates that KGF can activate an ARE in a promoter without reactive oxygen species involvement and that KGF and Dex can synergistically activate the PRDX6 promoter and protect cells from oxidative stress.
  
  
  CONCLUSIONS
  These two different activators work through different DNA elements. Their combined effect on transcription of the reporter gene is synergistic; however, at the protein level, the combined effect is additive and protects cells from oxidative damage.
authors.affiliation: 1 Institute for Environmental Medicine, Perelman School of Medicine, University of Pennsylvania , Philadelphia, Pennsylvania.
authors.forename: Ibrul
authors.initials: I
authors.lastname: Chowdhury
authors.forename: Aron B
authors.initials: AB
authors.lastname: Fisher
authors.forename: Melpo
authors.initials: M
authors.lastname: Christofidou-Solomidou
authors.forename: Ling
authors.initials: L
authors.lastname: Gao
authors.forename: Jain-Qin
authors.initials: JQ
authors.lastname: Tao
authors.forename: Elena M
authors.initials: EM
authors.lastname: Sorokina
authors.forename: Yu-Chin
authors.initials: YC
authors.lastname: Lien
authors.forename: Sandra R
authors.initials: SR
authors.lastname: Bates
authors.forename: Sheldon I
authors.initials: SI
authors.lastname: Feinstein
mesh_terms: D000818:Animals; D061745:Antioxidant Response Elements / Q000235:genetics; D003907:Dexamethasone / Q000008:administration & dosage; D051523:Fibroblast Growth Factor 7 / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D051379:Mice; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D054465:Peroxiredoxin VI / Q000096:biosynthesis* / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000187:drug effects; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics*
chemical_list: D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse; D017382:Reactive Oxygen Species; D051523:Fibroblast Growth Factor 7; D003907:Dexamethasone; C515977:PRDX6 protein, human; D054465:Peroxiredoxin VI